Why AirShaper - Complementing the Big Boys - Ansys Fluent, Siemens StarCCM+, Exa PowerFlow and others

Why AirShaper - Complementing the Big Boys - Ansys Fluent, Siemens StarCCM+, Exa PowerFlow and others
Wouter Remmerie
Wouter Remmerie


When I made the transition from university to industry, I was truly shocked:

no longer did I have time to solve problems purely from a technical point of view with fairly large amounts of time to do so. Things had to be delivered within someone else's planning and very often that lead to good but non-perfect solutions. After being trained for 5 years to pursue mechanical perfection, I had to deliver 5 solutions which were "good enough" instead of 1 perfect solution.

I felt dirty :)

⌚A Time and Place for Everything

Truth is though, if you zoom out, this makes sense in many cases: rapidly creating 5 different designs and testing them (physically or digitally) will create a lot more insight than perfecting one. You're still chasing that technical solution, just like at university, but the path that leads to it is very different.

One doesn't exclude the other: over time I have come to appreciate that there is a time and place for everything. If you're working on fundamental research, you need to work extremely in-depth to make sure the foundations are correct - after all, real-world applications & products will be built on top of your research at some point. But if you're working on those real-world applications & products, you'll be faced with rapidly changing market demands, customer desires, product release cycles and much more. So taking the time to perfect things might leave you with a perfect yet outdated product by the time you launch.

It's the undeniable, perverse nature of our economic system :)

☝My First Encounter with Aerodynamics & CFD

My first encounter with aerodynamics was a gut-feeling based sports car I designed in my free time, featuring internal & external air channels to generate lateral aerodynamic forces. No tools involved, just love for physics. Without tools, I could only go a certain length and although the concept got patented and I got to talk to Ferrari (who referenced to my patent in theirs) & Pagani (I got to meet them at their office!), the project died.

Patented Concept for Lateral Aerodynamic Force Generation
Patented Concept for Lateral Aerodynamic Force Generation

Later, when I started running actual CFD (computational fluid dynamics) simulations and wind tunnel tests when working at Belgian engineering agency Voxdale, this fed (and corrected) my internal physics engine. Feeling real wind, seeing turbulence on your computer screen, putting tufts on a car, ... it all helps.

Back then, we worked with FloEFD by Mentor Graphics. It's based on a modified k-epsilon RANS solver - not top of the line but not too basic either and very user friendly. Exactly what we needed in terms of accuracy versus cost versus throughput time for all the race car, drone and building projects we were doing.

⛓50 Shades of CFD

So why, then, was FloEFD bought by Siemens? They already had StarCCM+, a top of the line software package widely used in automotive for example. Well, each software package has its unique trade-off: StarCCM+ has all the tricks & options you need to achieve that ultimate accuracy, but you'll see some black snow before you get to the good stuff & produce reliable results. FloEFD, on the other hand, is much more accessible, and you'll still be able to work with it if you haven't used it for a year and want to jump back in.

Many CFD software solutions exist in the market
Many CFD software solutions exist in the market

Siemens is not the only one offering a range of CFD software packages though. Dassault Systèmes, who also offer Solidworks, merged Exa Powerflow, another highly-reputed aerodynamic simulation software package, into their offering. Whether it's StarCCM+, Powerflow, Ansys Fluent or Altair Hyperworks, they each have their own blend of user features, cost, ease of use and so on - all of them aimed at skilled CFD engineers. Choosing a package comes down to your budget, obviously, but also your skillset, timeline and most of all application.

⚡Common Challenges

In the case of AirShaper, that application is external aerodynamics. The field of many fascinating product developments such as cars, trucks, buses, planes, drones, sports equipment and even athletes! As you can imagine, the aerodynamic skills of the users performing simulations vary tremendously, from "never touched CFD software before" to "I eat CFD for breakfast" (CFD not meaning "crunchy fried doughnut" if you were wondering 😎)

Whatever the background or skill of the user, they all need to cope with similar challenges:

  • Getting the 3D model: 3D files are often not available for a racecar (manufacturers don't exactly hand those out), let alone a 3D model of an athlete!
  • Fixing the 3D model: Very often, depending on the software, a 3D geometry needs to be made watertight (meaning all gaps & holes need to be closed). A tedious, time-consuming task.
  • Setup complexity: Setting up a simulation usually requires a sound degree of expertise, as there are literally dozens of parameters that can influence the simulation stability and results
  • Meshing: Meshing is the key to a proper CFD simulation (although some interesting meshless solutions are becoming more popular). It's one thing to get a proper initial mesh, it's another thing to refine it properly during the simulation (something called adaptive mesh refinement)
  • Hardware: Unless your name is Adrian Newey, you'll need a computer to solve your aerodynamics problem. With ever-rising demands on accuracy, the hardware needed is often comprised of tens or hundreds of cores and Gigabytes or even Terrabytes of RAM memory.
  • Post-processing: Once a simulation is done, you'll need to process the results into data and visuals that are easy to understand. Only then can you start to understand the problem after which you can redesign & re-calculate new design options.

🔗General Purpose or Application Specific

If you're running all types of simulations on different applications (like a consultancy agency) you may favour a general-purpose CFD software package. This will allow you to apply thermal simulations for one project, compressible flow for another, and so on. If you're an expert, this is a really cool option, because you can control every single parameter: You're an expert, you know what to do. You're in charge of 3D model fixing, meshing, solving, post-processing and so on.

Or, you can go for an application-specific CFD software package: there are solutions tailored to aviation, supersonic flows, and - you guessed it - incompressible external aerodynamics, our playing field at AirShaper. The cost of such packages is typically much lower as you don't have all the options. And setup us much easier, as unnecessary features are removed.

⏲The Right Time for the Right CFD Software

You could also consider combining software packages, especially in bigger firms: as a designer, you can be working on initial concepts which are then, after months of work, sent to the engineers for review. After fixing the 3D model (if you're the designer, you may spend some weeks on this), they'll run simulations and let you know what and where to change the design.

The good thing is that each person does what they are best at: the designers design and the engineers crunch numbers. The bad thing is that this creates isolation & underappreciation for each other's domain. The designers get annoyed when something needs to be changed because of the aerodynamics and the engineers complain that the designers keep suggesting unrealistic shapes. So giving the designers an easier-to-use version of that aerodynamics software solution could work miracles.

Also, this greatly reduces the development time: using a fast & flexible simulation tool in the early stages of design quickly sets you off on the right track. That avoids months of rework compared to when you only run the first simulation after months of work, only to find out there are serious issues.

❔Why AirShaper

So why, then, did we start AirShaper? Well, we like StarCCM+, Ansys Fluent, Exa Powerflow, Altair Hyperworks and so on. But just like I was struggling myself to get my hands on some initial feedback of the car I was designing 12 years ago, so are others.

An easy to use, online platform that:

  • works with non-watertight 3D models (including 3D scan files)
  • takes automated control of all simulation parameters
  • automatically creates & adaptively refines the mesh
  • drops a simulation report in your mailbox when it's done
  • costs less for a one-year subscription than the yearly maintenance cost of a general-purpose CFD software

really makes the complex domain of aerodynamics accessible to a much broader audience.

And, interestingly enough, we also have a good deal of CFD experts using AirShaper as well: yes, they still love to control everything, but quickly firing 10 comparative simulations in the cloud at the very early stages leaves their hands free to work on more customized simulations for other projects.


All of the software packages discussed above have their right of being: when extreme accuracy levels are required, you simply need a CFD expert to control the buttons and a software package with... enough buttons. But there is a whole parallel universe where fast and accurate simulations greatly help to speed up design work, increase insight and even enable companies without previous CFD simulation expertise to inject some aero-magic into their products.

That's why we run AirShaper. And we're proud to complement the big boys like StarCCM+, Powerflow and Fluent.

More information:

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